Lateral flow assays and other types of calorimetric assays are used for a variety of diagnostic tests, including food safety tests, water quality tests, and medical tests such as home pregnancy and drug tests. Some diagnostic tests, such as drug tests, typically involve an initial screening test to identify those samples that test positive for the presence of drugs or particular chemical components. A confirmation test is then performed on the samples that test positive to identify the specific drug or chemical components present in the sample.
Usually screening tests are performed locally and confirmation tests performed at a centralized laboratory. For example, a drug screening test can be performed on potential or current employees at an employer work site or local doctor's office and the confirmation tests performed at a centralized medical laboratory. U.S. Pat. No. 6,716,393 by Lappe et al. discloses a test system for automatic testing of fluid samples. An assaying device includes a collection cup and a cap that visibly houses at least one test strip. The collection cup stores the fluid sample to be tested. An electrically-powered reader device applies a downward force to a piston and plunger element in order to deliver an aliquot from the fluid sample to the one or more test strips. Included in the reader device are a camera and a processor. The camera captures images of the one or more visible test strips and the processor analyzes the captured images to determine the results of the test.
Although the system described in U.S. Pat. No. 6,716,393 provides an automatic method for testing fluid samples, the system is limited in its portability. The size and weight of the assay reader device can limit is use in the field. Moreover, the assay reader device must be located near a source of electrical power in order to perform and complete the tests.